(HealthDay News) – Serum concentrations of perfluorinated chemicals (PFCs), which have been widely used in various household products for years, are linked with changes in thyroid hormone levels in women and men, according to research published online July 17 in the Journal of Clinical Endocrinology & Metabolism.

Li-Li Wen, PhD, of En Chu Kong Hospital in New Taipei City, Taiwan, and colleagues analyzed data for 1,181 participants, older than 20 years, from the National Health and Nutrition Examination Survey in 2007–2008 and 2009–2010 to examine the relationship between serum levels of PFCs and thyroid function in the general U.S. population.

The researchers found that the geometric mean concentrations of common PFCs were 4.15ng/mL for perfluorooctanoate (PFOA), 14.2ng/mL for perfluorooctane sulfonate (PFOS), 1.54ng/mL for perfluorononanoic acid (PFNA), and 2ng/mL for perfluorohexane sulfonate (PFHxS). After weighing for sampling strategy, one-unit increases in natural log-serum concentrations of PFCs were found to be associated with an increase in serum total triiodothyronine of 6.628ng/dL in women for PFOA; increases in total thyroxine of 0.26µg/mL and total triiodothyronine of 4.074ng/dL in women for PFHxS; and a decrease in free thyroxine of 0.016ng/dL in men for PFHxS.

“To our knowledge, this is the first report to link serum PFC levels and thyroid measures in a nationally representative survey of U.S. adults,” the authors write. “These findings suggest an effect of low-dose PFOA and PFHxS in humans, although the potential biological significance of this effect is small and subclinical in the general U.S. population.”

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